1. Field of the Invention
The present invention relates generally to the field of plumbing installations, especially during building construction. More specifically the present invention relates to a barrier plug assembly for incorporation into a lower portion of a new plumbing installation such as in a building under construction, for supporting a column of test water or to retain air or inert gas for inspection. Air or inert gas are sometimes required to find leaks prior to water testing, and to perform such a test the top of the plumbing installation is physically capped with an air fitting or a CBP is placed on top and an air fitting is added to the installation. The barrier plug assembly includes a tubular plumbing segment having a smooth and continuous plumbing segment interior surface and a barrier plug adhering to the interior surface and extending diametrically across and sealing the plumbing segment interior, the barrier plug having a plug upper surface and a plug lower surface, and having a plug circumferential surface adhering to the plumbing segment interior surface and being formed of dehydrated material which absorbs water and weakens when a test column of water is introduced onto the plug upper surface. Once this weakening occurs, the plug can no longer support the weight of the column of test water and therefore breaks and collapses so that the plumbing installation is opened for operation. The plug fragments dissolve and drain out of the installation with the water. The tubular plumbing segment preferably is either a pipe or fitting.
The plug is caused to adhere to the plumbing segment interior surface by any suitable molecular engagement means. A first such means is molecular adhesion. A second such means is creating molecular adhesion with a bonding agent or adhesive such as glue to secure the plug to the plumbing segment interior surface. A third such means is plug expansion into snug high friction contact with the plumbing segment interior surface. A fourth means is press fitting the plug into the tubular plumbing segment.
The plug material must support the column of test water for a sufficient length of time prior to collapse during which inspection can take place. This test water support duration is provided in any of several ways, including selecting plug material which dissolves at a suitable rate. A second way is to design the plug to have a maximum strength exceeding the force of the weight of the intended column of test water by a specific amount, and then after inspection adding water to the test column until the pressure reaches a designed plug failure point and the plug collapses. A third way is to form the plug of a chemical composition which is weakened or dissolved by the presence of a counteracting chemical, and then adding the counteracting chemical to test water.
2. Description of the Prior Art
There have long been barrier assemblies including barrier plugs for blocking and sealing tubular plumbing segments at the lower end of plumbing installations so that a column of test water can be retained above the barrier plug and throughout the installation for inspection. A problem with these barrier assemblies has been that they typically require a mechanical mechanism for breaking the barrier to release the test water to a drain pipe and thereby to open the plumbing installation for use. Such mechanisms add cost and reduce reliability. Another problem has been that some of the barrier assemblies include an irregularity along the interior surface of the tubular plumbing segment such as a ledge, recess or gap to support the barrier plug or a physical cap to isolate the plug, which then requires additional labor to remove, cut or break. Plumbing codes specifically forbid the inclusion of such surface irregularities, because debris can accumulate on the irregularity and gather until the pipe or fitting is clogged.
One prior barrier assembly is disclosed in Carney, et al., U.S. Pat. No. 4,607,644 issued on Aug. 26, 1986, disclosing a plumbing test plug apparatus including combined mechanical apparatus and a frangible plug requiring substantial labor and material, also leaving a gap after releasing test water. Carney requires a mechanical band to install a frangible plug. The Carney design relies on applying external mechanical pressure to break the plug, and when dislodged the missing plug leaves an internal gap at the installation location. Such a gap is forbidden by Chapter 4, entitled Prohibited Joints and Connections, at paragraph 4.7.1 and added explanatory section 706.2 of the National Plumbing Code, which does not permit the presence of gaps, recesses or ledges. The Code forbids the inclusion of gaps, ledges, or size reductions within drainage systems. In addition, the use of the Carney design is limited to installations with plumbing segments interconnected by bands. Mechanical band connections are nearly obsolete and have been replaced by solvent glue joints which now represent the greater part of the market.
Duncan, U.S. Pat. No. 6,267,001 issued on Jul. 31, 2001, teaches a test plug in the form of a combined mechanical and partially dissolvable tablet to support a column of test water. Substantial labor is required to retrieve parts following release of the test water. Duncan requires an internal ledge to house a partially dissolvable plug, but it must be placed in a fitting that has an opening in order to remove an air hose and balloon-like membrane that initially protects the plug from water contact.
Prenner, U.S. Pat. No. 3,924,677 issued on Dec. 9, 1975, reveals a device for use in the completion of an oil or gas well in the form of a water soluble plug assembly which requires welding to install and physical cutting to expose the plug. The structural strength of the plug is not relevant. Prenner requires a hole to be cut into the host pipe and a mechanical apparatus must be inserted into the pipe and welded in place. A dissolvable plug is encapsulated and is integral to the device. However a drill bit or boring equipment must be utilized inside the pipe to cut off a fixed cap to expose the plug to water.
O'Brien, et al., U.S. patent application Ser. No. 10/983,309 issued on Nov. 8, 2004 for a chemical barrier plug for hydrostatic and pneumatic testing reveals a cost effective and labor and material saving assembly which retains test water or air pressure for a sufficient period of time to be officially inspected without having to remove or actuate mechanical devices or install expensive test fittings with openings.
It is thus an object of the present invention to provide a plumbing barrier assembly including a barrier plug for incorporation into a plumbing installation to retain a column of test water for installation inspection in which the barrier assembly requires no internal gaps, ledges, size reduction or mechanical devices to hold or protect a dislodgeable barrier plug.
It is another object of the present invention to provide such a plumbing barrier assembly which requires no external or internal mechanical apparatus or removable parts to hold a dislodgeable barrier plug in a flow obstructing position or to dislodge the plug to permit test water drainage and to open the installation for use.
It is still another object of the present invention to provide such a plumbing barrier assembly which can be color coded so that in an installation where multiple barrier assemblies are needed, a particular dislodged plug can be identified.
It is yet another object of the present invention to provide such a plumbing barrier assembly which leaves no untested joints, requires no retrofitting, removal of parts, replacing threaded plugs or tightening of joints after inspection.
It is finally an object of the present invention to provide such a plumbing barrier assembly which is reliable and inexpensive to manufacture.